Children with mental retardation are four to five times as likely to have psychiatric disorders as are non-disabled children (Pfeiffer & Baker, 1994), although there has been relatively little study of the phenomenon beyond the basic epidemiology of the phenomenon. Our currently ongoing, prospective, longitudinal investigation is among the first to address multiple processes involved in the emergence of dual diagnosis in young children. The proposed continuation seeks to extend our investigation of early family processes and child self-regulatory competence into the middle childhood period (ages 6 to 9) when risk for most childhood psychiatric disorder is greatest, and adds school relationships and functioning to the predictive model. There are five primary aims to this proposed continuation: (1) to determine the dynamic influences of early and ongoing family processes and child regulatory capacities on the development of behavior disorders during middle childhood in children with mental retardation; (2) to identify those dynamic family processes that operate across the early to middle childhood period that promote social, behavioral, and emotional competence in these children; (3) to identify the role of school climate and school-based social and emotional competence across time on children's regulatory behavior and dual diagnosis status; (4) to assess the continuity in children's developmental state (particularly regulatory and cognitive abilities) across this period, and determine its contribution to the emergence of co-morbid behavior disorders; and (5) to continue to compare the above processes to those of a matched sample of normally developing children and their families. We propose to follow our current sample of 220 families (100 of which have children with a significant developmental delay) across the middle childhood ages of 6 to 9 years. We also propose to collect a new cohort of 80 children (between the age of 5 and 6) and their families, all of whom will meet criteria for having significant developmental delay. This research will detail the complex interplay of child developmental status, family and school functioning, self-regulatory capacity, and the emergence of dual diagnosis conditions during the high risk period of middle childhood.